Tractor



FIG. 1 is a left side view of a tractor showing our new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a front left side perspective view thereof;

FIG. 7 is a rear right side perspective view thereof; and,

FIG. 8 is an enlarged front view thereof.

A bottom view is omitted because it is plain and unornamental and forms no part of the subject matter of the claimed design. 

The ornamental design for a tractor, as shown and described. 